update_contact

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description must carry the full burden of behavioral disclosure. It only mentions the partial update nature but does not disclose side effects, idempotency, authorization requirements, or what happens if the contact does not exist. This is insufficient for a mutation tool.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single sentence that efficiently conveys the core action and the critical 'partial update' behavior. No unnecessary words, fully front-loaded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool has 7 parameters (including a nested object), no output schema, and no annotations, the description is far too sparse. It omits key contextual information such as what the response looks like, error handling, and constraints on parameters. It is not complete enough for agents to use effectively.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is only 29% (2 of 7 parameters have descriptions). The tool description adds no parameter information beyond what the schema provides, failing to compensate for the low coverage. This leaves agents without guidance on fields like email, firstName, lastName, metadata, and subscribed.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the verb 'Update' and the resource 'a contact by id', and adds the specificity of 'partial — only provided fields change'. This distinguishes it from sibling tools like create_contact (create) and delete_contact (delete), making its purpose unambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies that this tool is used when modifying an existing contact and that only provided fields are changed, but it does not explicitly state when to use alternatives like create_contact for new contacts. It lacks explicit when-not-to-use guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.